For the purposes of the present, the terms “supporting structure” and “structural frame” designate the load-resisting sub-system of a construction (architectural structure), i.e. the part of the construction that transfers and possibly absorbs the main load through interconnected structural components or members.
Supporting arch structures, in particular of arch bridges, belong to the oldest engineered forms of construction and have played a fundamental role in the development of all advanced societies. For many centuries, arch bridges were constructed from masonry, which conditioned the manner and methods of construction to such an extent that, even with the advent of the industrial revolution, the first iron bridges were constructed as arch (i.e. compressive load-carrying) structures. The introduction of modern materials permitted the adaptation of arch bridges for longer spans. The development of high-strength tensile steel in the twentieth century made it possible to construct arch bridges with spans of hundreds of meters especially by means of transferring the reaction forces away from the abutments to the bridge deck itself (tied arch bridges).
The traditional construction materials for structural components are concrete, steel and—nowadays to a lesser extent—wood. In the second half of the twentieth century, a new class of materials, fibre-reinforced polymers or plastics (FRP), slowly began to be considered as potential candidates as construction materials for addressing the limitations of concrete, wood and steel structures. These composite materials are most interesting for the construction industry due to their high strength, low weight and high corrosion resistance. Nevertheless, in spite of the continual reduction in their prime material cost, FRPs still remain relatively expensive in general, even when this handicap is offset on the long term by generally low life cycle cost.
The use of FRP in bridge construction has produced a number of interesting solutions for deck systems, described, for instance, in patents U.S. Pat. No. 6,108,998, U.S. Pat. No. 6,170,105 and U.S. Pat. No. 6,455,131. However, although the potential (in terms of their mechanical properties) for the use of FRPs materials in long-span bridges is very high, the current material prices and the lack of production methods capable of producing the large components at acceptable market prices has restricted the spreading of such materials in bridge construction, particularly for single spans in excess of ten meters. Although, in principle, the use of cheaper FRPs (such glass-fibre reinforced composites, GFRC) is an acceptable option for short spans or long pedestrian bridges, GFRCs have a rather low specific modulus which precludes them from use in stiffness-dominated bridge applications whenever spans in excess of a tens meters are called for. Of course, long bridges made from FRPs are viable if they are multiply supported; however, in certain locations, multiple supports are not always physically possible or are too expensive to implement. For these reasons, current construction and installation practice has only resulted in medium-length multi-span or short, single-span, beam bridges.
In civil engineering applications, there is a need for cost-efficient construction methods for erecting supporting structures, in particular with medium and long spans.
WO 90/13715 A1 discloses a method of constructing an arched building structure that uses lightweight elongate frames, pivotally connected to each other at one end, wherein the frames are lifted simultaneously so that the pivotal connection forms a ridge of the building structure. The free ends of the frames are anchored at abutments while the frames are held in the lifted position to form a three-pin arch frame building structure. U.S. Pat. No. 4,143,502 describes another method of constructing an arched building structure, wherein an elongate structural frame is bent into parabolic shape by lifting the medial portion thereof and fixing the opposed ends of the structural frame on abutments. When the ends are fixed, the flexed frame supports itself thanks to the abutments.